WASHINGTON ― The Trump administration’s decision to allow accused domestic abuser Rob Porter to stay on as a top White House aide for more than a year without a permanent security clearance is yet another reason the security clearance process at the White House needs “credible oversight,” a top House Democrat said Thursday.

Rep. Elijah Cummings (D-Md.), ranking member of the House Oversight and Government Reform Committee, called for this scrutiny in a letter to the committee chairman, Rep. Trey Gowdy (R-S.C.), which HuffPost obtained.

He claimed that Gowdy and other Republican members have previously blocked efforts to obtain information related to White House security clearances.

Democratic senators also requested an intelligence community investigation into security clearance protocol on Thursday, Politico reported.

Officials who have access to classified government information, like in the White House, must apply for security clearances. For someone like Porter, this process would involve an in-depth FBI background check that covers possible allegations of domestic abuse. But new reports surfaced this week claiming that Porter physically abused his two ex-wives, one of whom filed an emergency protective order against him. Those allegations may have affected Porter’s chances for a permanent security clearance at the White House, where he worked as staff secretary until his resignation on Wednesday.

Porter’s background check was ongoing, and he was operating under an interim security clearance, White House spokesman Raj Shah said Thursday.

It’s unclear whether Porter was granted a security clearance of any level at his prior job with Sen. Orrin Hatch (R-Utah.) But a source familiar with the matter told HuffPost that he did not have one when he briefly worked with the office of Sen. Rob Portman (R-Ohio) from June 2013 to March 2014. A spokesperson for Senator Mike Lee (R-Utah) also said that Porter did not have a security clearance when he worked with that office from 2011 to 2013—and did not disclose his protective order.

Cummings has requested that the House Oversight Committee obtain all paperwork Porter “was required to complete as a condition of White House employment,” which includes “forms for internal White House vetting” and “the FBI’s final investigative report on Robert Porter” by Feb. 22.

Meanwhile, Democratic senators wrote that they are “concerned over the apparent low and inconsistent threshold the Trump White House uses for obtaining an interim security clearance.”

Democrats have voiced their unease for months. Last month, Cummings and other House Democrats wrote to White House Chief of Staff John Kelly, asking for information related to the staff’s interim security clearance process and expressing concern about President Donald Trump’s son-in-law and senior adviser, Jared Kushner.

In Thursday’s letter, Cummings accused Gowdy of refusing requests to obtain documents regarding the security clearances of Kushner, former National Security Adviser Michael Flynn, and his son Michael Flynn Jr.

Gowdy’s office did not immediately respond to comment.

“If you had agreed to any of our previous requests for information on these matters,” Cummings noted, the White House would have been required to answer “key questions”—like “how Mr. Porter was allowed to remain in his position,” he said.